Two types of cataracts are currently being investigated. Sugar cataracts are initiated by the action of the enzyme aldose reductase. Effective means of delaying the onset of this type of cataract are being developed. The second type of cataract studied is the hereditary cataract. We have developed two strains of mice with hereditary cataracts. Both cataracts are of the osmotic type, but subtle differences observed indicate that they are initiated by different mechanisms.